Obesity is a major health problem in developed countries. In the United States, the complications of obesity affect nearly one in five individuals at an annual cost of approximately $40 billion. Except for rare pathological conditions, weight gain is often directly correlated to overeating.
One strategy for controlling the individual's food intake is via the use of intragastric volume-occupying devices. Such devices are placed in the stomach and occupy a portion of its interior. Properly placed and sized, the intragastric volumes provide the patient with a feeling of satiety after having eaten only a smaller amount of food. Typically, the individual's caloric intake is thus diminished due to the subjective feeling of fullness. There are a number of available volume-occupying devices. Many must be introduced using surgical or other complex gastric procedures.
Intragastric balloons have been in clinical use for several years. Their success in the treatment of certain individuals with morbid obesity is well accepted.
Published U.S. Patent Application No. 2004/0186502, U.S. Pat. No. 6,981,980, and published PCT application WO/2006/020929, to Sampson et al, each disclose inflatable, intragastric volume-occupying balloons including a valve that provides fluid communication into the balloon from outside the body. The '502 application further discloses a method for occupying some amount of stomach volume comprising the step of inserting the deflated balloon into the stomach through the esophagus, inflating the balloon by introducing an activating liquid through the self-sealing valve. Each document describes selection of polymers allowing gastric erosion of the balloon and causing its subsequent deflation.
Published PCT Application WO/2006/044640, to Baker et al, shows an implant used as a bariatric device situated along certain walls of the stomach to induce a feeling of satiation.
Published U.S. Patent Application 2004/0192582, to Burnett et al, shows a composition and a device that expands in the stomach after swallowing and provide a temporary, erodible volume and consequent diminution of gastric volume in the stomach.
U.S. Pat. Nos. 6,271,278 and 5,750,585, each to Park et al, show compositions of swellable, superabsorbant-hydrogel composites that may be used in gastric retention treatments for obesity.
U.S. Pat. No. 4,607,618, to Angelchik, discloses an intragastric device made up of semi-rigid skeleton members, collapsible to a shape, and having dimensions suitable for endoscopic insertion into the stomach through the esophagus.
U.S. Pat. No. 5,129,915, to Cantenys, relates to an intragastric balloon that is intended to be swallowed and that inflates automatically under the effect of temperature. The Cantenys patent lists three ways that an intragastric balloon might be inflated by a change in temperature. First, a composition of a solid acid and of a non-toxic carbonate or bicarbonate is temporarily kept from the fluid in the stomach by a coating of chocolate, cocoa paste, or cocoa butter. The chocolate coating is selected to melt at body temperature. Secondly, a citric acid and alkaline bicarbonate composition coated a coating of non-toxic vegetable or animal fat melting at body temperature may be used. When in the presence of water, the composition is said to produce the same result as does the earlier-discussed composition. Third, the solid acid and non-toxic carbonate or bicarbonate composition may be temporarily isolated from water by an isolation pouch of a low-strength synthetic material which is to break immediately upon swallowing. Breaking the isolation pouches causes the acid, carbonate or bicarbonate, and water to mix and to react, thereby inflating the balloon. The balloon itself is said to be made up of a modestly porous, but non-digestible material that allows slow deflation.
WO/2005/039458 shows a gastric constriction device that is to be mounted exterior to the stomach and cause feelings of satiation due to pressure on the vigil nerves of the stomach.
WO/2005/101983, to Dharmadhikari, shows an expandable composition that may be used as a gastric retention system, with or without the presence of ancillary drugs.
U.S. Pat. No. 5,783,212, to Fasihi et al, shows an expandable, erodible polymeric composition that may be used in drug delivery systems.
U.S. Pat. No. 6,733,512, to McGhan, describes an intragastric balloon having erodible patches that allow self-deflation of the balloon after a chosen period of residence in the stomach.
None of the cited documents discloses the bioerodible intragastric implant deliverable to the stomach by conventional oral administration that is described below.